A preliminary exploration of predictors of outcome and cognitive mechanisms of change in cognitive behaviour therapy for psychosis in people not taking antipsychotic medication.

Background: Cognitive behaviour therapy (CBT) has been shown to be effective in an open trial for people with psychotic disorders who have not been taking antipsychotic medication. There is little known about predictors of outcome in CBT for psychosis and even less about hypothesised mechanisms of change.
Method: 20 participants with schizophrenia spectrum disorders received CBT in an exploratory trial. Our primary outcome was psychiatric symptoms measured using the PANSS. Secondary outcomes were dimensions of hallucinations and delusions, self-rated recovery and social functioning, and hypothesised mechanisms of change included appraisals of psychotic experiences, dysfunctional attitudes and cognitive insight. We also measured patient characteristics that may be associated with outcome.
Results: T-tests revealed that several of the hypothesised mechanisms did significantly change over the treatment and follow-up periods. Correlational analyses showed that reductions in negative appraisals of psychotic experiences were related to improvements on outcome measures and that shorter duration of psychosis and younger age were associated with greater changes in symptoms.
Conclusions: CBT based on a specific cognitive model appears to change the hypothesised cognitive mechanisms, and these changes are associated with good outcomes. CBT may be more effective for those who are younger with shorter histories of psychosis.
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